OCCURRENCE OF FOSSILS 167 



at a depth of 12 to 20 feet below the crest of the ridge, while a mammoth's 

 tooth has been obtained from the eastern bar, near the town of York. 



Professor Hall stated many years ago that shells were said to have 

 been found in beach ridges in the state of New York, though he himself 

 had not seen them,* and there was a report more recently that marine 

 shells were found in the Hunter Street tunnel in Hamilton, but they 

 turned out to be Silurian brachiopods from drift boulders in the till. 

 Until recently this w^as all the evidence on record as to the character of 

 the Iroquois water. 



The opening of a sand and gravel pit two years ago by the city author- 

 ities of Toronto, near the Reservoir park, disclosed a few fresh water 

 shells, mostly in fragments. Last autumn the pit was opened more 

 extensively, and numerous shells were picked up by the writer, by the 

 workmen in the pit, and by students and others interested in geology. 

 As many of them were taken directly out of the undisturbed gravel, there 

 can be no doubt that the shells belong where they were found. They 

 include many specimens of Campeloma decisa, in general well preserved ; 

 a number of pleuroceras, probably of more than one species ; sph?eriums, 

 and badly worn portions of unios. 



These fossils occur 150 or 160 feet above lake Ontario and nearly 100 

 feet above the Don valle}^ deposits, a half mile awa}^, from which so 

 many shells have been obtained. The Don beds, beside lying so much 

 lower, seldom contain campeloma, the commonest fossil at the Reservoir 

 park gravel pit, so that these beds can not be confounded with the much 

 earlier interglacial deposits. 



The beds opened are evidently of Iroquois age. They are at the right 

 level, are coarsely stratified, cross-bedded beach deposits, and lean against 

 an escarpment of till about 25 feet high, a continuation of the Davenport 

 ridge, the old shore cliff of the Iroquois beach. There are really tw^o 

 gravel pits, an upper one north of the Canadian Pacific railway and a 

 lower one south of it. The shells are found only in the deeper layers 

 not reached in the upper pit, though the two excavations are evidently 

 in the same deposit. 



Fossils from other raised Beaches 



The conclusion that the Iroquois water was fresh is entirely what 

 might have been expected, since other postglacial deposits of the Great 

 Lake region have already been shown to contain fresh water shells. 

 Warren Upham reports unios and sphseriums from lake Agassiz,t and 



*Geol. of New York, part iv, 1843, p. 349. 



t Warren Upham : Glacial Lake Agassiz, U. S. Geol. Survey, vol. xxv, p. 237. 



